ErythropoiesisStimulating

Erythropoiesis-stimulating agents (ESAs) are drugs that increase red blood cell production by stimulating the erythropoietin receptor on erythroid progenitor cells in the bone marrow. They mimic the action of endogenous erythropoietin, a hormone mainly produced by the kidneys in response to low oxygen levels, and thereby raise hemoglobin and hematocrit.

Common ESAs include epoetin alfa and epoetin beta, darbepoetin alfa, and, in some regions, longer-acting pegylated forms such as methoxy polyethylene glycol-epoetin beta. These agents differ in half-life and dosing frequency but share the goal of enhancing erythropoiesis to reduce the need for blood transfusions in appropriate patients.

ESAs are used primarily to treat or prevent anemia associated with chronic kidney disease and to manage chemotherapy-induced anemia in cancer patients. They are also used in certain other conditions where erythropoiesis is diminished, such as Zidovudine-related anemia or rare marrow failure disorders, with decisions guided by potential benefits and risks.

Administration is by intravenous or subcutaneous injection. Dosing schedules vary by product and indication, with some forms given weekly and others every two to four weeks. A hematologic response typically appears within one to two weeks, with further increases over subsequent weeks. Therapy aims to reduce transfusion requirements while maintaining hemoglobin at levels appropriate for the underlying condition, and excessive increases are avoided due to safety concerns.

Safety considerations include hypertension, thromboembolic events, and rarely pure red cell aplasia caused by antibodies against erythropoietin. Adequate iron stores are necessary for a response, and iron deficiency should be corrected before or during ESA therapy. ESAs are used at the lowest effective dose, and treatment should be reassessed if targets are not met or if risks outweigh benefits.